Oil burner

ABSTRACT

A gun type oil burner with a restriction plate in the barrel upstream of the nozzle and having annularly spaced orifices with swirl effecting flanges thereon to produce a rotational spin of air within the barrel. This is combined with narrow peripheral orifice slots in the plate, radially outwardly of the first named orifices. The latter project a sheath of air axially along the inner annular surface of the blast tube which surrounds the rotational swirl of air. Said swirling air mass is then constricted at the burner outlet, at which point atomized fuel is added to form a combustible mixture, which is immediately ignited.

United States Patent [191 Flournoy et al.

[111 3,820,944 June 28, 1974 OIL BURNER Inventors: Norman E. Flournoy;David A.

Morris, both of Richmond; Raymond Trippet, Highland Springs; Julian H.Dancy, Richmond, all of Va.

Assignee: Texaco Inc., New York, NY. Filed: Nov. 6, 1972 Appl. No.:303,882

Related U.S. Application Data Continuation-impart of Ser. No. 104,043,Jan. 5, i971, abandoned.

U.S. Cl 431/265, 239/405, 431/183 Int. Cl. F23q 3/00 Field of Search431/265, 181, 182, 183;

References Cited UNITED STATES PATENTS 2/1971 Walker et al. 43l/l83Primary Examiner-Edward G. Favors Attorney, Agent, or Firm-T. H. Whaley;C. G. Reis 5 7] ABSTRACT A gun type oil burner with a restriction platein the barrel upstream of the nozzle and having annularly spacedorifices with swirl effecting flanges thereon to produce a rotationalspin of air within the barrel. This vis combined with narrow peripheralorifice slots in the plate, radially outwardly of the first namedorifices. The latter project a sheath of .air axially along the innerannular surface of the blast tube which surrounds the rotational swirlof air. Said swirling air mass is then constricted at the burner outlet,at which point atomized fuel is added to form a combustible mixture,which is immediately ignited.

6 Claims, 5 Drawing Figures PAIENTEBJUH28 B74 3; 2 0.94

sum 1 0r 2 XLIEKM PAIENIEDMZB m4 SHEET 2 8F 2 1 OIL BURNER The presentis a Continuation-in-Part of an original 1 projects a conical pattern offinely atomized fuel particles into a highly turbulent flow of air whichemanates from the end of an elongated blast tube or barrel.

More specifically, the present invention concerns a structuralengagement for improving and facilitating the efficiency of combustionby forming a more combustible mixture. Innumerable expedients have beenproposed for effecting combustion by producing an ideal intermixture offinely divided fuel particles in the stream of air. This demands for onething, an extreme fineness of subdivision of the oil particles. Itrequires also however a high degree of turbulence of the air stream suchthat atomized fuel particles are instantaneously and uniformlydistributed throughout the air stream. I

Similar developments along this line are disclosed and claimed in US.Pat. No. 3,694,136 and US. Pat.

No. 3,664,804. These constructions, along with that of the presentinvention, relate to what can be colloquially referred to as high headburner. In such a unit the air stream in the blast tube is highlyrestricted or throttled by a barrier which controlledly meters thestream of air to the burner tip. More importantly, such a structureenables its control and disposition in the form of predetermined jetstreams which may be disposed and caused to cooperate to effect maximumturbulence and intermixing with the atomized fuel particles.

The present invention achieves this result in large measure by providingan elongated blasttube. The latter is so constructed that air flowingaxially therethrough is passed under relatively high pressure through aseries of weirs or apertures. The effect is to form a controlled, highvelocityturbulence within the air stream emanating from the tip of thegun barrel or blast tube. 1

' More particularly, the present invention involves the provision of aseries of rotationally or tangentially directed orifices for producing ahigh rotational spin of expanding air in the extremity or discharge endof the gun barrel. These rotationally directed orifices are annularlyspaced and located radially outwardly from the central axis of the gunbarrel. Further, they are spaced a predetermined distance inwardly fromthe rim or inner wall thereof. In combination therewith the inventionprovides an annularly spaced series of apertures or orifices disposedpreferably in close proximity to the inner wall of the blast tube, andspecifically between the inner wall of the blast tube and therotationally directing orifices.

Therefore, the last named axially directed orifices direct streams ofair exactly parallel to the axis of the blast tube, but essentiallyalong the inner wall thereof.

Since the blast tube is preferably cylindrical in shape, the resultingaxial streams provide a relatively high speed blast or jet of air whichforms a sheath along the inner surfaces of the blast tube.

Because, moreover, this sheath is desirably relatively narrow in aradial direction it desirably occupies the entire surface of thecylindrical blast tube. The series 2 of orifices are preferably,therefore, in the form of elongated narrow slots.

Applicants do not desire to be bound by any statement of theory. Inappears however that the combination of the relatively thin sheath of.high velocity air flowing axially along the surface of the blast tube,together with the spinning or rotational action of the intemal jets ofair, facilitates general rotation and thus the high degree of turbulenceat the extremity of the burner.

As described in certain of the aforementioned patents, the provision ofa frusto conical tip on the extremity of the blast tube enables therapidly rotating jets of air to be constricted through a relativelynarrow orifice or choke. Thus, the effective rotational speed andturbulence are further increased. To this end the end cone of the burnertip tapers in a downstream direction to a restricted central opening,coaxial there with.

With the air stream now constricted and at maximum turbulence, anatomized fuel stream is introduced thereto at a point adjacent to theblast tube narrowed outlet. Simultaneously, the air/fuel mixture isignited such that the resulting flame assumes a rapidly swirling, thoughexpanding pattern.

Reference is now made to the figures of the drawing wherein oneillustrative embodiment of the invention is disclosed in detail. In thedrawing, FIG. I is an oblique view of the extremity of the blast tube ofa gun type burner embodying the present invention, portions being brokenaway to show the internal structure as well as to symbolize thecooperation of the various air streams; FIG. 2 is a section takencentrally on the axis of the burner of FIG. 1; FIG. 3 is a transversesection taken on the line 3-3 of FIG. 2; FIG. 4 is a side elevation ofthe burner assembly and FIG. 5 is an end view thereof, facing the tip ofthe oil burner.

The present embodiment comprises a blast tube 10 which, as shown inFIGS. 4 and 5, projects from a plenum chamber 12, enclosing a typicalrotary or squirrel cage type of fan (not shown) driyen by motor 14. Airflows into the interior of the fan from inlet chamber 16 via openings18. The ignition controls are largely centered in the box 20 and theliquid fuel is handled by pump 22 and pipe 24.

The general function of the foregoing elements is conventional and thusis not describedin further detail, except to say that the fan ispreferably provided with a substantially higher speed andcorrespondingly higher power drive, such as, for example, to double thespeed of the blower. This is necessary, as will hereinafter more fullyappear, to maintain flow through the various orifices, of a highlyrestrictive barrier or partition, to set up high velocity jets orstreams of high kinetic energy air.

Referring now to FIGS. 1, 2 and 3, the internal structure comprisesinsulators 26 and electrodes 28, as well as a central, axial fuel pipe30, which terminates in nozzle 32. These members are similarlyconventional and, as before, the central pipe usually forms a supportingstructure for the electrodes and insulators as shown by means ofmounting bracket 51.

The latter, in turn, is supported by a partition plate or barrier 34.Said plate is circular in shape to fit the interior of the blast tube,and extends transversely thereacross as shown in FIGS. 1 and 2. Plate 34is attached to the mounting bracket through a spacer block 52 withscrews 53.

Inasmuch as the plate 34 is apertured to receive the fuel tube 30 andthe cylindrical insulators 26, these are likewise supported near theextremity of said blast tube. Likewise the entire assembly can bewithdrawn from the rear of the blast tube in known manner as de sired.

The main bulk of the air flow through the blast tube is directed throughH-shaped apertures 36. Actually, as is more apparent from FIG. 1, theseapertures 36 have an effective opening considerably larger than mightseem from elevation as viewed in FIG. 3. They are, however, as indicatedin FIG. 3, rectangular in shape with the long margins arranged in ageneral tangential or annular direction. The apertures transversemargins are disposed in an approximate radial direction with respect tothe axis of the. blast tube.

The last named or so-called margins of apertures 36 are provided withflanges or swirl vanes which are deformed or pressed out on oppositesides of plate 34 as at 38 and 40 respectively. These flanges bothextend in an annular and axial direction with respect to the blast tubeand make'approximately the same angle with the plane of plate 34. Theresult is to direct the high pressure air streams issuing from theupstream side of plate 34, at a high velocity and, at the same time, ina spiral or swirling direction. Inasmuch as tab or flange 40 is presseddownstream, and the inner flange 38 extends in an upstream direction,the net result is a rapidly swirling flow of air through the respectivejets, which air flows in a counter-clockwise direction as viewed in FIG.1.

FIG. 1 illustrates more or less diagrammatically how an air jet streamsfrom one of the several major orifices to form a continuous high speedswirl.

It is also important to note that the construction of the presentorifices has a high element of economic attractiveness in view of thefact that the I-I-shaped orifices can be formed by the least expensivesort of stamping operation.

Referring to the aforementioned sheath of air which flows axially alongthe interior cylindrical wall of the blast tube, attention is directedto the slotted orifices 42. The latter, as will be noted, are relativelynarrow, elongated slots arranged in annularly spaced relationship.Obviously they could be arranged in a curved, annular path, for thepresent purposes; however this has not been found to be necessary. Thedesired result is realized by the normal tendency of the flat jets ofair to follow the curved wall of the blast tube and to expandcircumferentially therealong. The overall effect is to create whatamounts to a more or less continuous sheath or film of axially flowingair under considerable kinetic force. Further said continuous sheathembraces and encloses the aforementioned rotational spiralling streamsof air.

Finally, the combined air drafts strike the inner surface of the frustoconical burner tip designated generally as at 46. Said tip ischaracterized by an interior frusto conical wall 48 extendingsubstantially inwardly in a radial direction and at the same time,downstream in an axial direction. The tip terminates in central apertureor constriction 50. Therefore, the axially flowing blast of air isturned or deflected inwardly by the surface 48 without being materiallyimpeded or reduced in velocity. It finally emanates as a highlyturbulent, spiralling mass from aperture 50.

Therefore, in operation, a high pressure mass of air in the chamber justupstream of the partition plate 34 blasts through H-shaped apertures 36.Said apertures initiate a main central flow of air with a high degree ofrotational spin which represents considerable kinetic energy.Simultaneously a flat, narrow sheath of air flowing axiallyfromapertures 42 sheathes the interior wall of the blast tube.

While it is not desired herein to be bound by a statement of theory, itappears that the sheath of axially flowing gas at the wall, in effect,facilitates the high velocity spinning action of the central flow. Inessence, the swirling stream is segregated from the frictionalresistance inherent in rotational flow across the interior surface ofthe blast tube. Thus, in effect, suspended in a somewhat friction freeenvironment the spinning action is greatly enhanced. Also the movementof the spinning mass in an axially downstream direction is obviouslypromoted by the rapidly moving axial jet stream forming the surfacesheath.

To shape the burner flame pattern to fit relatively long cylindricalcombustion chambers, central orifices 54 are added whereby to lengthenthe spiral of the air flow pattern.

In any event, the constriction of the choke or orifice formed by thefrusto conical tip of the burner finally merges the entire series ofstreams into an even more rapidly rotating mass of highly turbulent air.Into said mass the atomized liquid fuel spray from the nozzle 32 isprojected in a generally conical stream whereby to be efficiently mixedtherewith.

Irrespective the theoretical considerations involved, the net result hasbeen found to be a substantial improvement in the combustion whichfollows intermixing of fuel to define the combustible mixture.

The following example tends to illustrate the effect of the presentinvention as applied to a standard burner. In accordance with theinvestigation, said standard burner was first subjected to testing, andwas thereafter modified in accordance with the present invention. Thetests were then repeated.

The modifications consisted exclusively in removing the swirl producingvanes of the original burner and substituting the partition memberprecisely as disclosed in the figures of the present drawing. A furtherchange was the substitution of a 3,450 RPM drive motor, for the 1,725RPM drive motor, to maintain the plenum pressure necessary to permitorifice flow sufficient to reach comparable air-fuel ratios.

The air plate or barrier used in the present embodiment had a 4 inchdiameter, thus enabling it to fit the interior wall of the cylindricalblast tube. The H- apertures were sized, in the plane of the plate withdimensions of /8 inches by inches. The peripheral slots were as shown,eight in number, having a width of l/ 1 6 inch, and were approximately/2 inches long in a peripheral direction.

Following are the results of the comparative smoke number tests on thetwo burners wherein A represents the Paragon burner as received and Bthe modified burner as above:

Smoke Number Excess AirPercentage A 4 21 A O 43 B 0 I4 We claim:

1. In a gun type burner having an elongated cylindrical walled blasttube, including opposed upstream and outlet ends, and being communicatedat said upstream end with a source of air, said blast tube being adaptedto form a swirling air stream prior to intermixing into said stream of aliquid fuel, whereby to provide a combustible mixture comprising highlyatomized fuel particles and air, and means at the outlet end of saidblast tube for igniting the swirling combustible mixture, and a fuelnozzle positioned substantially coaxially of said blast tube, beingcommunicated with a source of liquid fuel and having a fuel dischargeport disposed adjacent to said blast outlet tube outlet end,

an air plate disposed transversely of said blast tube at the upstreamend thereof forming a partition thereacross,

said air plate having at least one air flow directing aperture spacedradially outwardly from the central axis of said blast tube, butinwardly from said tube cylindrical wall, said aperture having radialmargins provided with air swirl effecting flanges projecting therefrom,and including vanes arranged in the same swirl producing directionwhereby to form air passing therethrough into high velocity streamsrotating toward said tube outlet, relatively narrow orifice slots formedin said air plate positioned between said at least one air flowdirecting aperture and said blast tube wall, said orifice slots beingrelatively narrow in a radial direction but'elongated in an annulardirection,

said narrow orifice slots being annularly spaced to form a high velocityblast of air along the inner cylindrical wall of said blast tube,thereby defining a circumferential sheath about said swirling airstream,

the downstream end of said blast tube including a constricted openinghaving a lesser diameter than the diameter of said blast tube, and beingfurther defined by an end wall extending inwardly from said tube innerwall, whereby to choke the combined air streams prior to addition offuel thereto for forming a combustible mixture.

2. In an apparatus as defined in claim 1, wherein said constrictedopening in said blast tube end is disposed substantially concentric withsaid tube.

3. In an apparatus as defined in claim 1, wherein said constrictedopening in said blast tube end includes a conical wall extendingoutwardly toward and connected with said tube inner wall.

4. In an apparatus as defined in claim 1, wherein said fuel nozzledischarge port is positioned intermediate said constricted opening andsaid air plate.

5. In an apparatus as defined in claim 1, including air orifice meansdisposed inwardly of said orifice slots to direct air coaxially of saidblast tube inwardly of said swirling air stream.

6. In an apparatus as defined in claim 1, wherein said at least one airflow directing aperture in said plate comprises a plurality of saidapertures disposed about i said plate to form a plurality of highvelocity streams rotating in a common direction.

1. In a gun type burner having an elongated cylindrical walled blasttube, including opposed upstream and outlet ends, and being communicatedat said upstream end with a source of air, said blast tube being adaptedto form a swirling air stream prior to intermixing into said stream of aliquid fuel, whereby to provide a combustible mixture comprising highlyatomized fuel particles and air, and means at the outlet end of saidblast tube for igniting the swirling combustible mixture, and a fuelnozzle positioned substantially coaxially of said blast tube, beingcommunicated with a source of liquid fuel and having a fuel dischargeport disposed adjacent to said blast outlet tube outlet end, an airplate disposed transversely of said blast tube at the upstream endthereof forming a partition thereacross, said air plate having at leastone air flow directing aperture spaced radially outwardly from thecentral axis of said blast tube, but inwardly from said tube cylindricalwall, said aperture having radial margins provided with air swirleffecting flanges projecting therefrom, and including vanes arranged inthe same swirl producing direction whereby to form air passingtherethrough into high velocity streams rotating toward said tubeoutlet, relatively narrow orifIce slots formed in said air platepositioned between said at least one air flow directing aperture andsaid blast tube wall, said orifice slots being relatively narrow in aradial direction but elongated in an annular direction, said narroworifice slots being annularly spaced to form a high velocity blast ofair along the inner cylindrical wall of said blast tube, therebydefining a circumferential sheath about said swirling air stream, thedownstream end of said blast tube including a constricted opening havinga lesser diameter than the diameter of said blast tube, and beingfurther defined by an end wall extending inwardly from said tube innerwall, whereby to choke the combined air streams prior to addition offuel thereto for forming a combustible mixture.
 2. In an apparatus asdefined in claim 1, wherein said constricted opening in said blast tubeend is disposed substantially concentric with said tube.
 3. In anapparatus as defined in claim 1, wherein said constricted opening insaid blast tube end includes a conical wall extending outwardly towardand connected with said tube inner wall.
 4. In an apparatus as definedin claim 1, wherein said fuel nozzle discharge port is positionedintermediate said constricted opening and said air plate.
 5. In anapparatus as defined in claim 1, including air orifice means disposedinwardly of said orifice slots to direct air coaxially of said blasttube inwardly of said swirling air stream.
 6. In an apparatus as definedin claim 1, wherein said at least one air flow directing aperture insaid plate comprises a plurality of said apertures disposed about saidplate to form a plurality of high velocity streams rotating in a commondirection.